基于层次分析法的盐池县地质灾害危险性评价

Geological disaster hazard assessment in Yanchi County based on AHP

为探讨区域地质灾害危险性评价方法,在充分研究盐池县地质灾害孕灾环境的基础上,以多源遥感数据和基础地质数据为数据源,选择地层、岩组、土壤、土地利用类型、坡度、坡向、地形湿度指数、径流强度指数、距河流距离、距道路距离、归一化植被指数以及降水量等12个因子,利用GIS提取因子信息,采用层次分析法(analytic hierarchy process, AHP)建立评价因子及其类型的判断矩阵,构建地质灾害危险性评价指数,对盐池县地质灾害危险性进行评价和分区,划分出极低、低、中、高和极高危险区5类分区并完成精度检验。结果表明:①极低、低危险区的面积分别占全县面积的34%和28%,主要分布在盐池县中北部的丘陵区,中危险区面积约占全县的25%,主要分布在南部麻黄山、王乐井以西以及道路周边地区,高和极高危险区分别占总面积的12%和1%,主要集中分布在河流两侧以及麻黄山地区;②成功率曲线和受试者工作特征(receiver operating characteristics, ROC)曲线与横轴围成的面积(area under curve, AUC)分别为0.77和0.89,检验结果精度较好,同时,灾害点密度从极低危险区到极高危险区呈增加趋势且极高危险区的灾害点密度最大,达到了1.076个/km 2;③AHP方法适用于盐池县地质灾害危险性评价,评价结果可为盐池县地质灾害的防范与治理提供一定的参考依据。

In order to discuss the regional hazard assessment method of geological disaster, the authors, based on the comprehensive study of hazard-formative environments of Yanchi County, extracted twelve conditioning factors, i.e., strata, lithology, soil, land use type, slope, aspect, topographic wetness index (TWI), stream power index (SPI), distance to river, distance to road, normalized difference vegetation index (NDVI) and precipitation in the evaluation and information of factors by employing GIS with remote sensing data and geological data. Then the judgment matrix of conditioning factors and factor classes were constructed by analytic hierarchy process (AHP) method, and geological disaster hazard index (GDHI) was built. Finally the geological disaster hazard of Yanchi County was assessed and the resulted hazard map was classified into five classes, including very low, low, moderate, high and very high hazard. Meanwhile validation of the hazard map was performed using success rate curve and receiver operating characteristics (ROC) technique. The results are as follows:①The area percentage of very low and low class accounts for 34% and 28% respectively, mainly distributed among the middle and north of hill region;the area percentage of moderate class accounts for 25%, mainly distributed in the area of Mahuang Mountain, western Wanglejing and two sides of the main roads;the area percentage of high and very high class accounts for 12% and 1% respectively, mainly distributed in the area on two sides of rivers and Mahuang Mountain.②The area under curve (AUC) value of success rate curve and ROC is 0.77 and 0.89 respectively, which shows a reasonable validation accuracy of hazard assessment. At the same time, disaster density shows the characteristics of a continuing increase in the density values from the very low class to the very high class, and the density of the very high hazard class has maximum value with 1.076/km^ 2.③AHP method was successfully used to assess the geological disaster hazard of Yanchi County and AHP is suitable for hazard mapping in this region. The evaluation results could provide a reference for the prevention and control of geological disasters in Yanchi County.